JP3854680B2 - Pressure partition and exposure apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, in the X-ray extraction window and the like used in the exposure chamber of the X-ray exposure apparatus, and a EXPOSURE device using pressure bulkhead and which blocks the two different atmosphere of pressure.
[0002]
[Prior art]
An X-ray exposure apparatus that uses synchrotron radiation emitted from a charged particle storage ring or the like, that is, SR-X-ray or the like as exposure light, has a beam duct from a light source to an exposure chamber in order to avoid attenuation of X-rays by the atmosphere. An X-ray extraction window is used as a pressure partition for blocking the atmosphere between the exposure chamber having a low vacuum or a reduced-pressure atmosphere such as helium gas or the same atmosphere as the atmosphere and the high-vacuum beam duct. Is provided.
[0003]
The X-ray extraction window has a thin film made of a material having a high X-ray transmittance, such as beryllium, silicon nitride, silicon carbide, diamond, etc. This thin film is made of X-ray to avoid loss of X-ray energy. And the mechanical strength required to withstand the pressure difference between the beam duct and the exposure chamber.
[0004]
FIG. 6 shows an X-ray extraction window E _{0 according} to a conventional example, which has a beryllium foil 111 of several μm to several tens of μm and a flange 112 that supports the outer periphery of the beryllium foil 111. The outer peripheral portion is fixed to the flange 112 by an adhesive ring 113. The flange 112 is fixed to the flange portion 102 a and the like of the beam duct 102 by the bolt 115 via the O-ring 114.
[0005]
As described above, the beryllium foil 111 only withstands the pressure difference ΔP between the pressure P ₁ of the beam duct 102 maintained at a high vacuum and the pressure P ₂ on the exposure chamber side controlled in a reduced pressure atmosphere of helium gas. Mechanical strength is required, and the X-ray transmittance is required to be high. That is, it is desirable to make the beryllium foil 111 as thin as possible within a range in which the mechanical strength can be secured.
[0006]
In general, when a differential pressure p is applied to a very thin film made of a material having a Young's modulus E to cause a large deflection, assuming that the thickness of the film is h, the tensile stress σ ( r = 0) and the tensile stress σ (r = a) at the outer periphery are calculated by the following equations, respectively.
[0007]
σ (r = 0) = 0.423 · (E · p ² · a ² / h ² ) ^1/3 (1)
σ (r = a) = 0.328 · (E · p ² · a ² / h ² ) ^1/3 (2)
Therefore, the thickness of the beryllium foil 111 is set so as not to exceed the tensile stress σ _{1 of the} beryllium foil 111 at the time when the beryllium foil 111 is bent due to the pressure difference ΔP. It is common.
[0008]
That is, when the fracture stress of the beryllium foil 111 is σ ₀ and the allowable value of the pressure difference ΔP applied to the beryllium foil 111, that is, the design pressure is P ₀ , the necessary thickness T is expressed as follows from the equation (1). .
[0009]
T> 0.275 · P ₀ · a / σ ₀ · (E / σ ₀ ) ^1/2 (3)
In designing the X-ray extraction window, considering the safety factor A, the thickness T ₀ of the beryllium foil 111 is selected using the following equation.
[0010]
T ₀ = A · 0.275 · P ₀ · a / σ ₀ · (E / σ ₀ ) ^1/2 (4)
[0011]
[Problems to be solved by the invention]
However, according to the above prior art, even if the thickness of the beryllium foil is set using the equation (4), the beryllium foil may actually be damaged at a pressure difference lower than the design pressure P ₀ . The safety factor A must be designed large. Thus, the damage of the beryllium foil that occurs at the design pressure P ₀ or lower is observed at the contact portion with the flange that fixes the outer peripheral portion, but cannot be prevented by simply chamfering the corner of the flange. .
[0012]
When the safety factor A is increased, the beryllium foil becomes thicker than necessary, the X-ray transmittance cannot be increased, and energy loss increases, resulting in a decrease in productivity of semiconductor products and the like.
[0013]
The present invention has been made in view of the unsolved problems of the prior art, the mechanical strength is sufficient, yet extremely pressure bulkhead and an exposure apparatus having the same can Rukoto using a thin film It is intended to provide.
[0014]
[Means for Solving the Problems]
Pressure bulkhead of the present invention to achieve the above object, has a thin film for partitioning the two atmosphere different pressures, and a support member for supporting at its outer periphery a thin film, in the support member, wherein An inner peripheral edge arranged in a relatively low-pressure atmosphere of the two atmospheres is directed from the relatively high-pressure atmosphere side to the low-pressure atmosphere side of the two atmospheres in the axial direction of the inner periphery. It is characterized by having a curved surface in which the inner diameter and the inclination decrease .
[0015]
Radius of curvature of the curved surface, tensile and stress σf Ri generated in the outer peripheral portion of the thin film by bending along the curved surface, the pressure difference between the two atmosphere and the central and the peripheral portion of the thin film by the thin film is bent may is the radius of curvature by Ri large when pulling each generation caused stress sigma ₁ and the difference between the sigma ₂ are equal.
[0016]
Radius of curvature of the curved surface, may from the atmosphere side of the low pressure are hand increases as it suited to the atmosphere side of the high pressure.
[0017]
[Action]
The thickness of the thin film for partitioning two atmospheres with different pressures is designed so that it can withstand the tensile stress generated at the center of the thin film when it is deflected by the pressure difference between the two surfaces. The tensile stress generated at the center of the thin film due to the deflection due to the pressure difference is larger than the tensile stress at the outer peripheral portion, but the tensile stress generated due to bending due to contact with the support member is added to the outer peripheral portion. Therefore, there is a possibility that a larger tensile stress than the center is applied.
[0018]
Therefore, a supporting lifting member for supporting along songs surface having a large radius of curvature the outer peripheral portion of the thin film is provided, to reduce the tensile stress occurring due to the bending due to contact with the support member.
[0019]
If the maximum tensile stress of the entire thin film is the central tensile stress without the tensile stress generated at the outer periphery of the thin film exceeding the central tensile stress, the safety when designing the thickness of the thin film as described above There is no need to unnecessarily increase the coefficient.
[0020]
As a result, the thin film can be made thinner and the X-ray transmittance and the like can be increased.
[0021]
Such pressure bulkhead by using as the X-ray extraction window and the like, if the effective use of X-rays, etc., can greatly improve the productivity and the like of the exposure light device.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 shows an X-ray extraction window E ₁ which is a pressure partition according to an embodiment and a part of an X-ray exposure apparatus using the same. The X-ray extraction window E ₁ is located between the exposure chamber 1 and the beam duct 2. Arranged. As will be described later, an X-ray L ₁ such as SR-X-rays generated from a light source 3 (see FIG. 3) such as a charged particle storage ring passes through a beam duct 2 kept in an ultra-high vacuum, and an X-ray extraction window. E ₁ is introduced into the exposure chamber 1.
[0024]
The inside of the exposure chamber 1 is controlled to a reduced pressure atmosphere of helium gas, for example, about 0.2 Pa. This is because X-ray attenuation is prevented and heat dissipation of the wafer W _{1 and the} like is promoted by convection of helium gas.
[0025]
The X-ray extraction window E ₁ has a beryllium foil 11 that is a thin film of several μm to several tens of μm, and a flange 12 that is a support member that supports the outer periphery of the beryllium foil 11. It is being fixed to the flange 12 by. The flange 12 is fixed to the flange portion 2 a and the like of the beam duct 2 with bolts 15 through the O-ring 14.
[0026]
As described above, the beryllium foil 11 can only withstand the pressure difference ΔP between the pressure P ₁ of the beam duct 2 kept at a high vacuum and the pressure P _{2 of the} exposure chamber controlled in a reduced pressure atmosphere of helium gas. Mechanical strength is required, and high X-ray transmittance is required. That is, it is desirable to make the beryllium foil 11 as thin as possible within a range in which the mechanical strength can be ensured.
[0027]
Therefore, the beryllium foil 11 is calculated from the tensile stress σ _{1 at} the center of the beryllium foil 11 when the bend is generated by the allowable value of the pressure difference ΔP, that is, the design pressure P ₀ , using the above-described equation (4). The thickness T ₁ is set.
[0028]
However, even in the situation where the central tensile stress σ ₁ does not exceed the fracture stress σ ₀ , the outer peripheral portion of the beryllium foil 11 may be damaged due to the stress concentration at the contact portion between the beryllium foil 11 and the flange 12. . Therefore, the curved portion 12a having a curved surface of a predetermined radius of curvature R at the inner periphery of the flange 12 is provided, the curved surface of the curved portion 12a is brought into contact with the outer peripheral portion of the beryllium foil 11, it is curved along the tracks surface Thus, the stress concentration is prevented and the beryllium foil 11 is prevented from being damaged.
[0029]
When the outer peripheral portion of the beryllium foil 11 is curved along the curved surface of the curved portion 12a , the tensile stress σf generated thereby is the tensile stress σ ₂ generated due to the deflection due to the pressure difference ΔP between the exposure chamber 1 and the beam duct _2. Is added to
[0030]
Therefore, the curvature radius R of the curved surface of the curved portion 12a of the flange 12 is set as follows. As shown in FIG. 2, when the beryllium foil 11 is bent due to the pressure difference ΔP and the outer peripheral portion of the beryllium foil 11 is bent along the curved surface of the curved portion 12 a of the flange 12, the outer periphery of the beryllium foil 11 is The tensile stress σt generated in the portion is the sum of the tensile stress σ ₂ generated due to the deflection due to the pressure difference ΔP and the tensile stress σf generated by bending along the curved surface of the curved portion 12a of the flange 12. is there. That is,
σt = σ ₂ + σf (5)
Tensile stress σf is calculated by the following equation from the thickness T ₁ of the curvature radius R and the beryllium foil 11 of the curved surface of the curved portion 12a.
[0031]
σf = 0.5 · E · T ₁ / R (6)
From Equation (6) and Equation (2),
σt = 0.328 (E · ΔP ^1/2 · a ^1/2 / T ₁ ² ) ^1/3 + 0.5 · E · T ₁ R (7)
When the pressure difference ΔP is the design pressure P ₀ , in order for the tensile stress σt generated at the outer periphery of the beryllium foil 11 to be smaller than the tensile stress σ ₁ generated at the center of the beryllium foil 11, formula (7) And from equation (1)
R> 5.263 · (E ² · T ₁ ⁵ / P ₀ ² / a ² ) ^1/3 (8)
That is, the curvature radius R of the curved surface of the curved portion 12a of the flange 12 may be selected so as to satisfy the expression (8).
[0032]
Actually, since the tensile stress generated slightly inside the outer peripheral edge of the beryllium foil 11 is larger, the curvature radius of the curved surface of the curved portion 12a of the flange 12 is changed from the low-pressure atmosphere side to the high-pressure atmosphere side. It is desirable to increase gradually.
[0033]
If the outer peripheral portion of the beryllium foil is curved along the curved surface having the radius of curvature set as described above, there is no possibility that a larger tensile stress than the center is generated in the outer peripheral portion of the beryllium foil. If the thickness of the beryllium foil is designed based on the tensile stress at the center of the beryllium foil, there is no possibility that the beryllium foil will be damaged. Therefore, it is not necessary to increase the safety factor unnecessarily as in the conventional example. That is, the required thickness of the beryllium foil can be reduced to greatly improve the X-ray transmittance.
[0034]
FIG. 3 is a view showing the entire X-ray exposure apparatus. The X-ray L ₁ which is synchrotron radiation in the form of a sheet beam emitted from the light source 3 into the beam duct 2 is expanded by the convex mirror 4 in a direction perpendicular to the orbital plane of the radiation. The X-ray L ₁ reflected and magnified by the convex mirror 4 is introduced into the exposure chamber 1 through the X-ray extraction window E ₁ and is adjusted by the shutter (not shown) so that the exposure amount in the exposure region becomes uniform. The X-ray L _{1 that} has passed through the shutter is guided to the mask M ₁ . A wafer W _{1 as} a substrate is vertically held by a wafer chuck 5 as a substrate holding means, and an exposure pattern formed on the mask M ₁ is exposed and transferred onto the wafer W ₁ by a step & repeat method or the like. The wafer chuck 5 is positioned with high accuracy in six axial directions by a wafer stage 6 having a fine movement stage 6a and a coarse movement stage 6b.
[0035]
Next, an embodiment of a semiconductor device manufacturing method using the above-described X-ray exposure apparatus will be described. FIG. 4 shows a flow of manufacturing a semiconductor device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.). In step S11 (circuit design), a semiconductor device circuit is designed. In step S12 (mask production), a mask on which the designed circuit pattern is formed is produced. On the other hand, in step S13 (wafer manufacture), a wafer as a substrate is manufactured using a material such as silicon. Step S14 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step S15 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step S14, and is a process such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), or the like. including. In step S16 (inspection), the semiconductor device manufactured in step S15 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step S17).
[0036]
FIG. 5 shows a detailed flow of the wafer process. In step S21 (oxidation), the wafer surface is oxidized. In step S22 (CVD), an insulating film is formed on the wafer surface. In step S23 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step S24 (ion implantation), ions are implanted into the wafer. In step S25 (resist process), a photosensitive agent is applied to the wafer. In step S26 (exposure), the circuit pattern of the mask is printed onto the wafer by the X-ray exposure apparatus described above. In step S27 (development), the exposed wafer is developed. In step S28 (etching), portions other than the developed resist image are removed. In step S29 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device that has been difficult to manufacture.
[0037]
【The invention's effect】
Since this invention is comprised as mentioned above, there exists an effect as described below.
[0038]
A pressure partition which has sufficient mechanical strength and can use an extremely thin thin film can be realized. By using such a pressure partition as an X-ray transmission window, the productivity of the exposure apparatus can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an X-ray extraction window according to an embodiment.
FIG. 2 is a schematic cross-sectional view showing a state in which the X-ray extraction window of FIG. 1 is bent due to a pressure difference.
FIG. 3 is a diagram illustrating the entire X-ray exposure apparatus.
FIG. 4 is a flowchart showing a semiconductor manufacturing process.
FIG. 5 is a flowchart showing a wafer process.
FIG. 6 is a schematic cross-sectional view showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Exposure chamber 2 Beam duct 11 Beryllium foil 12 Flange 12a Curved part

Claims (4)

  A thin film for partitioning two atmospheres having different pressures, and a support member for supporting the thin film on the outer periphery thereof, and the support member is disposed in a relatively low-pressure atmosphere of the two atmospheres. The inner peripheral edge is curved in the axial direction of the inner peripheral edge, the inner diameter and the inclination of the two atmospheres decreasing from the relatively high-pressure atmosphere side toward the low-pressure atmosphere side. And pressure bulkhead. The curvature radius of the curved surface is a tensile stress σf generated in the outer peripheral portion of the thin film by bending along the curved surface, and the thin film is bent by the pressure difference between the two atmospheres, whereby the thin film is bent at the center and the outer peripheral portion. _2. The pressure bulkhead according to claim 1, wherein the difference between the tensile stresses [sigma] ₁ and [sigma] ₂ generated is equal to the radius of curvature when the difference is equal.   The pressure partition according to claim 1 or 2, wherein a radius of curvature of the curved surface increases from the low-pressure atmosphere side toward the high-pressure atmosphere side. 4. An exposure apparatus comprising: the pressure partition wall according to claim 1; and substrate holding means for holding a substrate exposed by X-rays transmitted through the pressure partition wall.

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